German Published Examined Application DE-AS 12 96 199 of 19 May 1969, DICKINSON/IBM DEUTSCHLAND, discloses an apparatus for recording/retrieval of data by means of a magnetic head device which can be adjusted to arbitrarily selected tracks of a magnetic disk memory. As shown in FIG. 2, the magnetic head device has a working gap 15 for erasure of data, which gap is arranged, with reference to the tracking direction, ahead of an working gap 17 for the recording or retrieval of data. The track width of the working gap 15 for the erasure of data is greater than the track width of the working gap 17 for the recording/retrieval of data. The exciter winding of the gap for the erasure of data is selectively connectable, at a branchpoint, via one of two connecting leads, to a current source. The winding is connected in series with a rectifier and in parallel with a capacitor. This known apparatus erases using rectified current, with the result that phase distortions are apparent in the signal played back. These phase distortions are of the non-linear sort, and cannot be suppressed by using a linear equalizer.
Further European Published Application EP 0 280 326 A2, OKAMURA/TOSHIBA, discloses a magnetic head device consisting of a read/write system and two erasure systems limiting the width of the recorded track. The erasure systems, arranged downstream, in the direction of motion of the recording medium, from the read/write system, trim the previously accomplished recorded track, according to the so-called "tunnel-erasure" method, down to a predetermined useful track width.
As disclosed in European Published Application EP 0 170 004 A1, KUMASAKA/HITACHI, the two erasure systems are generally combined into a so-called tunnel-erase head, so that both erasure systems can be simultaneously controlled with a single head winding. However, since the erasure systems are separated, signal-wise, from the read/write systems, such a magnetic head arrangement requires a greater circuitry investment for generation and control of the recording and erasure signals.